The present invention relates generally to internetworking within a telecommunications system and more specifically to facilitating translation of signals between a Public Land Mobile Network (PLMN) and an IP-based network.
Wireless communication technology has experienced unprecedented growth, fueled by advances in radio frequency, satellite, and microelectronic technologies and by the convenience of access to telephony and portable cellular devices. A common architecture for wireless communication is the Global System for Mobile Communications (GSM) which is a protocol standard defined by the Conference of European Posts and Telegraphs (CEPT) for use in digital land mobile radio networks.
Likewise, the Internet has become a popular tool for sending and receiving information. In essence, the Internet comprises a worldwide network of communications equipment and service providers which use a common protocol for communicating. On the Internet, messages are transmitted from one user to another over a vast infrastructure of routers, servers, gateways and other similar devices. Typically, users on either end of the network operate computers equipped with appropriate software, devices and other components. Examples of such components include a modem and Internet browser application. Often, a user establishes a connection to the Internet through an Internet Service Provider (ISP). The underlying link level protocols stacks handle the messaging functions on both ends of the channel. Transmission Control Protocol/Internet Protocol (TCP/IP) is a connection standard developed by the U.S. Department of Defense in the 1970s that is utilized for IP-based networks. TCP governs the exchange of sequential data, while IP routes outgoing and recognizes incoming messages. Other protocols such as User Datagram Protocol (UDP), a connectionless protocol, are used to send information from one application to another on the Internet.
The widespread use of the Internet as a communications tool has led to an intense push for the integration of Internet services with other networks such as cellular networks including GSM. While IP networks communicate using TCP/IP connections, cellular networks utilize common channel signaling system number 7 (SS7 or C7), a global standard for telecommunications defined by the International Telecommunication Union (ITU) and specifically the Telecommunications Standardization Section of the ITU (ITU-T). The SS7 standard defines the procedures and protocols by which network elements in the public switch telephone network (PSTN) exchange information over a digital signaling network including wireless, e.g. cellular, and wireline call setup, routing and control. The ITU definition of SS7 allows for variance of the procedures and protocols such as those promulgated by the American National Standards Institute (ANSI) and Bell Communications Research (Bellcore) standards used in North America as well as the European Telecommunication Standards Institute (ETSI) standards used in Europe.
Essentially, an SS7 network and the defined protocols are used for implementing call signaling functions including basic call setup management and tear down. In addition, SS7 specifies various wireless services such as personal communication services (PCS), wireless roaming and mobile subscription authentication. Most recently, the SS7 protocol has been used for local number portability (LNP) as well as toll free and toll wireline services. Other services that benefit from the SS7 protocol include enhanced called features such as call forwarding, calling party name and number display and three way calling as well as a wide array of emerging applications standards that provide for efficient and secure worldwide telecommunication.
With an SS7 network, messages are exchanged between network elements over 56 or 64 kilobits per second (kbps) using bi-directional channels called signaling links. Signaling occurs out-of-band on dedicated channels rather than in-band on voice channels. Compared to in-band signaling, out-of-band signaling provides faster call setup times, more efficient use of voice circuits, and support for intelligent network services which require signaling to network elements without voice trunks. In addition, out-of-band provides for improved control over fraudulent network use. These advantages have made the SS7 protocol a popular choice for internetworking with voice over Internet Protocol (IP) applications including IP telephony.
The hardware and software functions of the SS7 protocol are divided into functional abstractions called levels. These levels map loosely to the Open Systems Interconnect (OSI) 7-layer model defined by the International Standards Organization (ISO). An ISDN user part (ISUP) defines the protocol used to setup, manage and release trunk circuits that carry voice data between terminating line exchanges, e.g., between a calling party and a called party.
The internetworking of IP networks with wireless networks such as the PLMN poses a challenge, because of the different communication protocols used. A function is required to translate IP address and TCP/UDP port number information from IP networks to SS7 information of a PLMN, and vice versa. Currently, when a serving or routing node such as a Network Access Controller (NAC) is added to an IP network, the translational information for facilitating communication between the IP-based networks and PLMNs must be configured manually within an IP-SS7 gateway. Such manual configuration is time-consuming, cost ineffective and prone to introduce errors.
The present invention provides a method and system for automatic configuration of a gateway translation function between an IP network and a PLMN. Upon system start-up or upon the addition of a NAC to an IP network, the NAC provisions the IP address and port number information of an associated IP-SS7 gateway that provides a link to the PLMN. The NAC establishes a connection with the IP-SS7 gateway and sends a registration message having IP address and port number information to the IP-SS7 gateway. The IP-SS7 gateway uses the information in the registration message to update its translation function, correlating the IP address and port number information to a numbering plan and digit string within the PLMN.
In one embodiment, disclosed is a method of facilitating automatic translation of signals between a PLMN and an IP-based network in a communications system having a gateway providing an exchange mechanism between the PLMN and the IP-based network. The IP-based network contains a Network Access Controller (NAC) configured to communicate with the gateway. The method comprises the steps of provisioning IP address and port number identifiers of the gateway within the NAC and sending a registration message from the NAC to the gateway, where the registration message contains the IP address and port information of nodes within the IP-based network.
In another embodiment, disclosed is a system for facilitating automatic translation of signals between a PLMN and a IP-based network. The system includes a gateway providing an exchange mechanism between the PLMN and the IP-based network, and a Network Access Controller (NAC) within the IP-based network providing signal control functions for a plurality of subscribers. The NAC is configured to provision IP address and port number identifiers of the gateway and send a registration message from the NAC to the gateway. The registration message contains the IP address and port information of nodes within the IP-based network.